Added an option to specify demo user, will be created on startup if it does not exist

internal/createuser/createuser.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"net/http"
+	"slices"
 	"strings"
 
 	"git.artlef.fr/PersonalLibraryManager/internal/config"
@@ -53,6 +54,11 @@ func CreateDefaultUsers(db *gorm.DB, config *config.Config) error {
 		usernames = append(usernames, splittedString[0])
 		usersPasswordMap[splittedString[0]] = splittedString[1]
 	}
+	if !slices.Contains(usernames, config.DemoUsername) {
+		usernames = append(usernames, config.DemoUsername)
+		usersPasswordMap[config.DemoUsername] = ""
+
+	}
 
 	var existingUsers []model.User
 	err := db.Where("name IN ?", usernames).Find(&existingUsers).Error